Widespread occurrence of low levels of alternariol in apple and tomato products, as determined by comparative immunochemical assessment using monoclonal and polyclonal antibodies

This study investigated the production of polyclonal (pAB) antibodies and the first time production of monoclonal (mAB) antibodies against the mycotoxin alternariol, and their implementation in enzyme immunoassay (EIA) for the rapid determination of alternariol in foods. Both EIAs were highly sensitive, with detection limits (IC??) of 35 ± 6.9 pg/mL (mAb EIA) and 59 ± 16 pg/mL (pAb EIA). Food products (n = 109; apple and tomato products, white wine) from German retail shops were analyzed. At a detection limit of 1-2 μg/kg, alternariol at 1-13 μg/kg was found with high frequency in apple (67%) and tomato (93%) products. Tomatoes with visible signs of Alternaria infection, stored at room temperature for up to 4 weeks, contained alternariol at levels up to 50 mg/kg, as determined by EIA and HPLC-FLD. It is concluded that the alternariol immunoassays present a versatile screening tool which could facilitate food control for Alternaria toxins.     

Quantitative assessment of rill and interrill soil erosion in Romania

Soil erosion is an important geomorphological process with potential negative consequences especially on land agricultural potential. Unsuitable agricultural practices may increase soil erosion, leading to rapid loss of soil fertility and decrease of crop production. It is therefore important to correctly quantify soil erosion rates in order to adapt agricultural practices and implement proper conservation measures. This study attempts to assess the rill and interrill erosion in Romania, using the Romanian soil erosion model and GIS techniques. The database includes the digital terrain model, the soil map of Romania, the land use map of Romania and the rainfall erosivity regions. The results show that the high and very high erosion risk classes include 4.1% of the Romanian territory (9,627 km²). Most of this land is present in the hilly and plateau areas (Subcarpathians, Moldavian Plateau, Getic Plateau, Western Hills, Dobrogea Plateau). The model was validated by comparison of its predictions with long‐term erosion measurements from different locations in the country. Comparison with previous non‐GIS assessments of soil erosion at national level shows that the total estimated rill and interrill erosion in our study was very close to previous estimates. Comparison with the RUSLE 2015 model computed for Europe as a whole reveals that the two models assign almost 54% of their shared area to the same erosion class, while for 39% of the territory there is one class difference between the models. The results can be used for evaluations of erosion risk at national and regional scales.     

Water deficit and corn productivity during the post-socialist period. Case study: Southern Oltenia drylands,Romania

Water deficit (WD) typically associated with drylands and poor land use currently represent a major limiting factor for agricultural systems in numerous regions of the world. The present study aims to analyze the relationship between water deficit and corn (Zea mays L) crop yields in southern Oltenia drylands. The study includes the post-1990 period, which is representative for Romania in terms of ample climate changes and poor land planning decisions affecting water resources. This analysis targeted the vegetation period of corn (April–September), the reference period covering a 14-year interval, from 1990 to 2003. The entire analysis was based on spatialized WD data (mm), obtained by interpolation methods used on climate data provided by regional weather stations, and agricultural yield data (tons/hectare/year), recorded in 113 administrative territorial units. Both data sets were analyzed in terms of interannual statistical relationships, established in compact climate zones delineated by Thiessen-Voronoi polygons. The results showed a clear statistical relationship between the two variables, with an average dependence of corn yields on water of approximately 65%. The range was from 55 to 78%, depending on region. The results showed an average yield decrease of 16.5 kg/ha/year for each mm rise of the WD, or loss of 1.65 t/ha/year when considering a deficit rise of 100 mm. Therefore, in the context of increasing future WD, urgent action is needed in order to reintroduce irrigation systems.     

Enzyme immunoassay for tenuazonic acid in apple and tomato products

The Alternaria mycotoxin tenuazonic acid was derivatized with succinic anhydride and conjugated to keyhole limpet hemocyanin (KLH) and to horseradish peroxidase (HRP), respectively. The KLH conjugate was used to produce polyclonal antibodies in rabbits. A competitive direct enzyme immunoassay (EIA) for tenuazonic acid was established, which was moderately sensitive for tenuazonic acid [50% inhibition concentration (IC(50)): 320 ± 130 ng/mL] but strongly reacted with tenuazonic acid acetate (IC(50): 23.3 ± 7.5 ng/mL). Therefore, an optimized EIA protocol was established, which employed acetylation of standard and sample extract solutions. The mean standard curve detection limit (IC(30)) for tenuazonic acid acetate was 5.4 ± 2.0 ng/mL, enabling detection limits for tenuazonic acid in apple and tomato products of 25-50 ng/g (150 ng/g in tomato paste). Recoveries in a concentration range of 50-2000 ng/g were 60-130% in apple juice and tomato juice and 40-150% in other tomato products. Tenuazonic acid was detected in apple juice and tomato products from German retail shops at levels of 50-200 ng/g. In conclusion, this novel EIA for tenuazonic acid could be useful within a screening program for Alternaria mycotoxins in food.